As valve timing change devices in the related art, a valve timing change device including a case and a cam sprocket (a housing rotor) that are synchronized with a crank shaft and rotate on an axis of a cam shaft; a movable member (a vane rotor) that demarcates an advance angle chamber and a delay angle chamber in cooperation with the case and rotates on the axis; a bolt that fastens the movable member to the cam shaft and has an oil passage (a port); a flow rate control valve that is constituted of a sleeve which is fitted into a thinned insertion portion to pass the center of the bolt and has an oil passage (a penetration portion), and a spool which is inserted into the sleeve to be freely reciprocating and opens and closes the oil passages (the port and the penetration portion), and the like; an advance angle oil passage and a delay angle oil passage that constitute ring-shaped grooves formed on an inner circumferential surface of the movable member in which an outer circumferential surface of the bolt is fitted; and the like is known (for example, refer to Patent Literature 1 and the like).
In this device, the quantity of oil guided in and guided out with respect to the advance angle chamber and the delay angle chamber respectively via the advance angle oil passage and the delay angle oil passage is adjusted by suitably controlling driving of the flow rate control valve.
Here, the sleeve is formed of a material having a thermal expansion coefficient greater than that of the bolt so as to prevent oil leakage or the like from a gap generated due to thermal expansion in a fitting interface between the sleeve and the bolt of the flow rate control valve.
However, there is no mention of a gap in the fitting interface between the bolt and the movable member. If the bolt is formed of an iron-based material and the movable member is formed of an aluminum-based material, a gap is generated in the fitting interface due to a difference in thermal expansion between both thereof, or the like.
As a result, there is concern that the advance angle oil passage and the delay angle oil passage individually formed as the ring-shaped grooves on the inner circumferential surface of the movable member will communicate with each other and oil will not be able to be guided to the desired oil passage.
In addition, the advance angle oil passage and the delay angle oil passage constituting the ring-shaped grooves provided on the inner circumferential surface of the movable member are generally formed by performing boring in which the movable member is fed in an axis direction and a radial direction using a boring machine or the like. Therefore, the processing with the configuration described above is troublesome compared to boring or counter-boring in which the movable member is simply fed in only the axis direction and a cylindrical surface is formed.